TB 55-5210 251-35/1
7. Accessories required. Table 3 identifies the accessories used in this calibration procedure. These accessories may
be substituted unless specifically prohibited.
Table 3. Accessories required
Item
Nomenclature
Minimum use
Accessory
No.
specifications
identification
B1
GAGE, HEIGHT
RANGE: 0-10 in.
5210-293-1932
VERNIER
ACCURACY: Nominal
B2
PLATE, SURFACE
RANGE: 8 in. x 24 in. size
5220-529-1373
ACCURACY: Nominal
Section III PRELIMINARY OPERATIONS
8. Preliminary instructions.
Note. Personnel should familiarize themselves with the entire bulletin prior to performing calibration.
9. Equipment setup.
a. The test instrument should be placed in the calibration area at least eight hours before calibration is performed for
temperature stabilization.
b. All working surfaces must be free of dirt, nicks, or rust.
c. Place test instrument in a convenient position on surface plate.
d. Adjust test instrument dial scale to exactly zero (0).
Section IV. CALIBRATION PROCESS
10. Beam linearity
a Performance check
(1) Select the proper combination of gage blocks (A1) equal to 6.0625 inches in height.
(2) Wring the gage block stack together and rest stack on surface plate (B2) as near as possible to the top
working surface of the test instrument.
(3) Attach the dial indicator (A2) to the vernier height gage (B1) and obtain a dial indicator mid scale reading
from the gage block stack. Note. Exact indication is unimportant but should be near mid scale on dial indicator.
(4) Set dial indicator (A2) scale to zero.
(5) Move the height gage (B1) laterally until the dial indicator (A2) stylus contacts the top working surface of test
instrument.
(6) Slide the vernier height gage along and in total contact with the surface plate (B2) until the length and breadth
of the test instrument (fig. 1) working surface has been contacted by the dial indicator stylus.
(7) The dial indicator (A2) must read within the limits of +0.002 inches of the zero setting.
b. Adjustments. No adjustments can be made.
11. Final procedure.
a. Dissassemble the gage block stack and replace the gage blocks and dial indicator in their respective containers.
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